Modern commodity wheat grain is classified as “red” or “white”. The classification is quite distinct because the modern “red” wheat varieties have been specifically bred to be of a particular hardness and type, which has a bran color that is usually dark and called “red”. Modern white wheat bred to have light colored bran is called “white“. It is less popular with the refined flour millers because it is generally soft and yields less refined flour than the (hard) red varieties, e.g. only 66% vs 76% refined flour respectively. However, makers of cookies, cakes and noodles really like this kind of soft wheat flour, hence its existence. “Hard white wheat” is a modern invention = white wheat suited to more efficient refined flour milling; it is also popular for lighter colored whole wheat products. The distinctly “red” modern wheat types can usefully resist pre-harvest sprouting in the field after ripening in wet summer weather. The distinctly “white” modern wheat types are generally grown in areas with completely dry summer conditions during ripening. If “white“ types are grown in regions with wet summers they are likely to sprout in the ear while still in the field, so reducing their ability to make a well risen bread. The fault is recognized using the “Falling Number” lab. test. Landrace wheat types are much more varied in their bran color than modern commodity wheat. There are many landrace varieties with a color intermediate between the two extremes of “red” and “white”. Since bran color, or kernel color, seems to be associated with ability to resist preharvest sprouting in the field it is likely that the depth of bran color suggests the degree of resistance to pre-harvest sprouting. Wheat with a purple bran color e.g. Ethiopian purple durum wheat is also seen among the landrace varieties.
The standard for industrial flour production introduced in the mid to late 1800's, in which a series of cylindrical rollers rotate at different speeds, shearing and crushing grain as it passes through the gaps. Designed to more efficiently remove all traces of bran and germ, in the service of creating high volumes of white refined flour.